


The King of Balance

by inspiration_assaulted



Category: Ao no Exorcist | Blue Exorcist
Genre: M/M
Language: English
Status: In-Progress
Published: 2015-05-28
Updated: 2016-10-27
Packaged: 2018-04-01 15:08:54
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 8
Words: 11,150
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4024489
Author URL: https://archiveofourown.org/users/inspiration_assaulted/pseuds/inspiration_assaulted
Summary: <blockquote class="userstuff">
              <p>Rin never could stop getting involved in fights, especially if it was to protect someone. Father Fujimoto died saving Rin from human thugs in a fight when Rin was only nine, but seeing Shirou's death awoke Rin's demon side. Abandoned by his twin, Rin finds help from his only other family: his brothers. Mephisto takes him into Gehenna to be raised as he should have been and to take his place as the last demon king, the King of Balance.</p><p>Six years later, Yukio is a certified exorcist and teaching in the cram school of the True Cross Academy. Rin is a fully trained demon king with a role in the future of Assiah and Gehenna that only a few know, but that does not stop him from keeping an eye on his twin.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> A/N: I would like to preface this story by saying that I know no Japanese and very little about the culture. I discovered Blue Exorcist because I have an interest in demons and demonology, and it is my first experience in manga/anime. Rather than make a fool of myself or a mockery of anything else, I use exclusively English terms. However, I do speak German, so Mephisto may use more German than he would in canon. I promise to translate!
> 
> Every chapter of this story will begin with a flashback. In the main action, Rin and Yukio are fifteen. It follows (to a point) the action of the anime series. The flashbacks will give some insight into what is happening in the main action, but they will not happen in order. I will try to make it as clear as possible how old Rin is in each one.

Rin tipped his head back and glared at the sun. What right did it have to be happy and shining when the man he had thought was his father was dead? It was a funeral, so the weather should be rainy. That’s how it always was in films.

His hat was hot and itchy. Rin wished he could take it off, but then everyone would see the pointed tips of his ears. His shirt was loose, though, so no one could see the tail he had wrapped around his belly.

The nine-year-old looked over at his brother, but Yukio just scowled and turned his head away. That hurt. Rin felt a new wave of tears well up, but he just wiped them away and knelt in front of the gravestone.

“I’m sorry, Shirou,” he whispered. “I should have listened to you. I should have tried harder.” He could still see the fire when he closed his eyes, a mix of yellow and unnatural blue.

The old man had warned him not to get in anymore fights, no matter what he saw, but he just couldn’t help it. The two guys had looked like they were almost twenty and they had been beating up a little kid in glasses. He just had to jump in, because the kid had reminded him of Yukio, and Rin always stood up for Yukio.

Shirou had found him there, being roundly beaten by the two guys. Rin didn’t really know what had happened next, but one of the guys had stabbed Shirou in the back. Something inside Rin had broken, and all he remembered was blue flames and screaming in pain.

Then Mephisto had appeared and told Rin he would help him and keep him safe. So Rin stayed with the strange man dressed like a clown, because Shirou had wanted him to be safe. Shirou told him to leave him behind and live.

Rin missed Shirou. He missed Yukio, too. His little brother wouldn’t talk to him anymore. He just glared, like he hated Rin more than anything else in the world.

“Little Brother.” Rin wiped away more tears and looked up. Mephisto’s colourful clothing seemed unnaturally bright in the cemetery, and he smiled kindly. “It’s time to go.”

Rin looked over at Yukio again, but Yukio walked away without looking at them. “Ok,” he said sadly. He took Mephisto’s hand and let him help him up and lead him out of the graveyard.

Maybe someday he would talk to Yukio and understand why his own twin brother seemed to hate him so much.

* * *

* * *

Rin sat in the shadows in a high corner of the cram school classroom. His tail swung freely below the heavy pipe he perched on. He watched the students gathering below him.

Three boys sat together at one table, two with colourful hair and one bald one. They interacted with the familiarity of long friends, but the one in the centre with the yellow streak was clearly the leader. He heard them call him ‘Bon,’ an honorific title.

Two other friends, both girls, sat together at another table. Rin didn’t think the brown-haired one would last long, but her purple-haired friend was arrogant enough to go far. She also had tiny, stupid-looking eyebrows. Rin termed her Eyebrows, deciding it was better than any name she might have.

Two more sat by themselves. One was a boy with a puppet on his hand that he spoke quietly to. Rin disregarded him. The second was a figure in boy’s clothes with a hood pulled down low, playing on a handheld game. Rin knew that aura well. It was Shura Kirigakure. No doubt she was there in case he or his elder brothers tried anything.

“Which are the ones Elder Brother told us about?”

Rin looked up at Amaimon, hanging from the ceiling with one hand. “Those.” He pointed at the three boys.

Amaimon dropped to sit next to Rin. “Survivors of the Blue Night,” he murmured. “They better not see you.”

Rin smirked. “Good thing Satan taught me how to control my flames, then, right?”

“Do they pose a real threat to you?”

“I won’t know until I see them in action.”

“Would you like to me to create some excitement for you, Little Brother?” Amaimon asked, turning his big, curious eyes on Rin.

Rin sighed. “You’ll do nothing, Amaimon,” he ordered. “By the Gate, I should keep you on a chain.”

Amaimon’s big eyes went even wider and he vanished without a sound.

The door opened and Yukio walked in. His eyes seemed dull behind his glasses, and Rin could pick out at least three guns holstered in and beneath his coat.

“Pleased to meet you,” he greeted. “I’m Yukio Okumura, your instructor for Anti-Demon Pharmaceutics.”

A few students greeted him, but Rin could see most of them were wondering why he was so young.

“Now, I’m actually the same age as you all, but I’ve been studying to be an exorcist since I was seven and just passed my test two years ago. I think it best if you all just call me ‘teacher,’ though.”

Rin reached into his pocket and took out the lollipop he had a feeling would be there. Amaimon liked leaving them in his pockets. If Rin didn’t eat it, his brother would just take it back from him the next time he wanted one.

“To the first order of business,” Yukio was saying. “Is there anyone here who has not received their Temptaint yet?” Three humans raised their hands, and Rin snorted. Such simple little people, wanting to be exorcists without even knowing the terror that was looking a demon in the eye at midnight.

Rin tuned out as Yukio explained the Temptaint ritual and about hobgoblins, the demons they would be calling up. He wrinkled his nose as Yukio uncorked a vial and the smell of rotten blood drifted back to him.

With a series of pops, half a dozen hobgoblins appeared in the room. They all turned to look at him, but Rin raised a finger to his lips and they turned back around. The little round demons sniffed and snuffled around the gathered would-be exorcists. The students jerked and twitched as the hobgoblins bit and scratched at their fingers and ankles.

One appeared with a little puff next to him. It wobbled, holding onto the pipe with one meaty fist and tapping the back of Rin’s hand with the other. Rin smiled down at his brother’s little familiar, taking the hobgoblin’s hand.

“Hello, Behemoth,” he whispered.

“Can everyone see them now?” Yukio asked. The few who needed the Temptaint still nodded. “Good.”

Behemoth let out a whine as Yukio pulled out a gun and destroyed the other hobgoblins in the space of a heartbeat. He growled as more hobgoblins appeared, bigger and angrier, and Yukio demolished them too.

“Behemoth, no!” Rin hissed, but the hobgoblin was already gone, growling and swelling as he advanced on Yukio. “Amaimon’s going to be mad,” he muttered, but he knew his elder brother better than that. Amaimon would be happy his little familiar could cause chaos on its own.

Rin let out a put-upon sigh and leapt from the pipe, landing lightly on two feet between Yukio and Behemoth. He snapped two long knives out with a motion only demon eyes could follow. Yukio’s guns clattered to the floor, released when Rin slapped the teen exorcist’s hands with the flat of his blades and pinched the nerves.

“Not that one,” Rin warned.

Yukio gasped, too stunned to even reach for another weapon. “Rin?”

Rin made an expression that somewhat resembled a smile. Yukio shuddered as he caught sight of long, sharp incisors. Rin ran the tip of his tongue over one, just to make sure Yukio knew what he was. “Yukio. Long time, no see.”

“Why are you here?” Yukio demanded.

“In the cram school?” Rin twitched when Behemoth nibbled at the end of his tail. It reminded him of what Amaimon and Mephisto always told him: a gentleman never shows his tail.

Yukio’s eyes followed the motion of his tail as he wrapped it around his waist. He scowled. “In Assiah,” he spat. “The Vatican should have killed you years ago. I should have killed you.”

“Years ago they might have let you,” Rin replied casually. “Do it now, and you’ll find yourself arrested for harming an ally of the Grigori.”

“What?!”

Rin decided Yukio was shocked enough to not attempt to attack anymore. “Come here, Behemoth.” Rin cradled the once-again-little hobgoblin in one arm. “Naughty little thing. You should have stayed in Gehenna.” He ignored the gasps of the would-be exorcists. They had much to learn. “Come see the director when your class is over,” he told Yukio.

“I will,” Yukio promised, nearly growling.

“Good.” Rin turned and walked toward the door. “I should return Amaimon’s familiar to him. Try not to get carried away.”


	2. Chapter 2

 

Light flooded Rin’s eyes as he stepped through his Gate. The yawning circle of darkness closed behind him without a sound, but Mephisto looked up from his desk anyway. Rin knew better than to even try to sneak up on his oldest brother in his domain. Mephisto knew everything that happened in his office.

“Hello, Littlest Brother,” the King of Time grinned.

“Elder Brother,” Rin nodded. He took of his jacket and slumped into a chair facing Mephisto. “What do you want to talk about now?”

“This.” Mephisto flicked something at him at a speed that made it blur.

Rin snatched the object inches in front of his face. “A card?”

“An ID card,” Mephisto corrected. “A copy, at least. Yukio Okumura’s official exorcist identification.”

Rin blanked his face to hide his turmoil of emotions, knowing Mephisto was watching him carefully. “He passed his exams, then,” he murmured. He tossed the ID copy back. “How do the other exorcists feel about having a thirteen-year-old working beside them?”

“They respect him a great deal. He was raised by the last Paladin, after all,” the older demon pointed out. “Fujimoto spent two years before his death personally teaching young Yukio. Most exorcists, including those at the Vatican, believe he will do great things.”

Rin hummed. He turned the information over in his mind, looking at it from every angle, just like Mephisto had taught him to over his years in Gehenna.

Very few angles looked good.

“How destructive is he?”

“Very,” Mephisto replied solemnly. “This year I can use his Novice status to watch him carefully, but next year…” he shook his head. “I have no doubt the Vatican will promote him quickly, and I will not always be able to keep a watch over him.”

“He will need to be watched, though,” Rin murmured.

Mephisto nodded. “I will make him a teacher after he is promoted. That way I can hold him here in the school without risk. He cannot do much damage while still being responsible for students.”

“I want to watch him,” Rin decided.

“Littlest Brother…” Mephisto sighed. “Are you sure?”

“Of course I’m sure!” Rin snapped. He took a deep breath and pulled his emotions back. “I am the King of Balance. Let me do my job, Elder Brother.”

Mephisto leaned back in his chair with a wide smile. “Very well, Little Prince.”

* * *

* * *

Rin stepped through the infinity key doorway and into Mephisto’s office. His older brother and caretaker looked up without even a trace of surprise.

“You let him see you already?”

Rin hopped up to sit on the back on an armchair, his feet on the seat and tail swinging free. He shrugged. “Behemoth was with me when he started taking out hobgoblins. I couldn’t let him kill Brother’s familiar, could I?”

Mephisto smiled that smile that gave away nothing. “You are very good with Brother.”

Rin just shrugged again. “Yukio will be here soon. He doesn’t believe I’m an ally of the Grigori.”

“Of course he doesn’t.”

Rin leapt off the chair and walked over to the window. The sun was setting over True Cross Academy Town. He had always liked watching the sun set from that window. On perfectly clear days, there was a second when the sun hit the perfect spot and it looked like the whole town was burning, reflecting the red sun from every window.

There were too many clouds that night for that magic second. Rin watched the growing dark anti-climax in silence. The only sound in the room was Mephisto’s scratching pen as he filled out some paperwork.

The door banged up as Yukio stomped in. “You better have a damn good explanation for why Rin’s out of Gehenna!”

“Such brotherly love,” Mephisto huffed. “When did you become so angry, Yukio Okumura?”

“When I saw that bastard again,” Yukio growled.

Rin turned to look at his human brother over his shoulder. “That bastard is right here,” he said blandly.

“I don’t care,” Yukio shot back. He glared venomously.

Rin sighed. “I would have thought exorcists were taught to control their emotions. There are a lot of demons that read human emotions.”

Yukio laughed coldly. “I was never the one who had a problem controlling myself!”

“No,” Rin agreed, “that was me. The first thing Sa- Father,” he corrected himself with a glance at the setting sun, “did was make me control myself before my flames destroyed Gehenna.”

Slipping out some of his power, Rin let his flames engulf the bushy end of his tail. He let them burn for a few seconds before he smothered them again.

“My control is complete,” he promised. “I’m not going to expose myself accidentally to your students from the Cursed Temple. Their little minds would explode.”

Yukio sneered and turned away from him. “How did he escape a death sentence from the Vatican?” he asked Mephisto.

Mephisto launched into a watered down explanation of Rin’s role in keeping to balance between demons and exorcists. Rin let the words wash over him and returned to looking out the window.

“A gentleman always covers his tail, Little Brother.” Cool fingers lifted Rin’s shirt as he wrapped his tail around his waist.

Rin looked back over his shoulder to smile at Amaimon. “You’d think I’d remember by now.”

“I guess six years isn’t enough for you,” Amaimon said. “Maybe after six hundred you’ll remember.” Amaimon’s hand slipped into his. “Elder Brother is being boring.”

Rin squeezed the King of Earth’s hand. “I’m being boring now, too,” he told him. “You should go back to Gehenna.”

Amaimon’s lower lip pushed out as he turned childishly wide eyes on Rin. “Gehenna’s boring.”

Rin leaned over to knock his their foreheads together lightly. “If you can sit through the boring part, we’ll go get ice cream, ok?”

Amaimon nodded and wandered over to play with Behemoth in the corner of the office.

Rin turned to find Mephisto watching him fondly and Yukio staring in shock and horror. “What, Yukio?”

“How can you be nice to a demon king? You act like you like him!”

Rin frowned. “I am a demon king, Yukio,” he said bluntly. “And of course I like him. He’s my brother.”

“I think, Little Brother,” Mephisto spoke up, “that you and Amaimon are closer than humans generally are with their brothers. You two do look very…romantic together.”

Rin just shrugged. “He’s like a kid, Yukio. He’s curious and a handful sometimes, but in six years he’s never changed the way he treated me. Can you say the same?”

Yukio flinched. “Rin…” he whispered, and just for a second Rin could see beneath his hard exterior to the scared little boy he still was inside. Then he scowled and his eyes went dull again. “No, maybe I can’t. But can you tell me that my brother was still the same person after that night?”

“Yes, I was,” Rin replied flatly. “I’ll be watching your classes, Intermediate Exorcist First Class Okumura. Amaimon, let’s get ice cream.”

“Wheee!” The way Amaimon cheered without changing his facial expression had long ago become endearing to Rin. The older demon prince opened a doorway with Mephisto’s infinity key and dragged Rin through by both hands.

* * *

Mephisto steepled his hands together and watched Yukio Okumura. Perhaps it had been cruel not to tell him about Rin’s activities in Gehenna, especially after the younger twin had become a full-fledged exorcist, but Mephisto very rarely indulged in such human emotions as guilt and regret.

“Your brother was nine years old when you refused to ever speak to him again,” he recited blandly. “Shirou trusted me to take care of Rin if something ever happened to him. Granted, he thought it would be demons hunting Rin when he was older, not two human thugs.” He saw Yukio’s jaw drop before he recovered himself. “Yes, you never asked about that night. Rin simply cannot stop himself from protecting others. He saw a boy who reminded him of you being beaten by two young men and jumped in to help the boy. He was hopelessly outclassed when Shirou found him-“

“Stop!” Yukio held up a hand, shaking. “I don’t want to hear it.”

“Very well.” Mephisto leaned back and propped his feet on his desk. “Simply find me if you ever wish to know more.”

Yukio stood and left the room. “I won’t.”

Mephisto winced as the door slammed. Human emotions were quite loud sometimes.


	3. Chapter 3

“Happy Birthday, Littlest Brother,” Mephisto said with his usual mysterious smile.

Rin just grinned and blew out his candles, shaped like the number eleven. His older brother had brought him into Assiah to the True Cross Academy and had his little cooking familiar bake a cake for him. “Can I cut it?”

“Not yet,” Mephisto shook his head. “We have to have a talk before it gets dark.”

Rin wanted to pout, but Father always said no son of Satan would ever pout over anything. “Ok,” he sighed instead. “But we can have cake after, right? And Amaimon can come?”

“Of course.” Mephisto ruffled his hair, making him squeal and struggle to get away. “Do you remember what I say about Assiah and Gehenna?”

Rin nodded. “Assiah and Gehenna are like a person looking into a mirror. Neither one can exist without the other,” he recited, proud of himself.

“Good,” Mephisto complemented. “Now, have you been watching and listening to Father like I told you too?”

“Yes, Brother.”

“Then can you tell me what Father really wants to do, more than anything else?”

Rin scrunched up his face as he thought. “He wants to open a huge Gate,” he said slowly, “so all the demons can come into Assiah and they can both be one world.”

“Very good,” Mephisto grinned. “Now, I want you to think about that really hard. Would that work? Is it a good idea?”

Rin did think very hard. He sat right down on the floor and thought, fiddling with the end of his tail until Mephisto took it out of his hands with a tsk. “The humans can’t go into Gehenna, right?” he asked. Mephisto nodded. “So that isn’t very fair, is it? If all the demons can come here, but humans can’t go there, then it isn’t really one new world. It’s just like…” he waved his hands, looking for the right words, “more Gehenna.”

“That’s exactly right,” Mephisto praised, making Rin smile. He felt very proud of himself when he made his older brother happy. “But if Assiah ceases to exist…”

“Then so does Gehenna,” Rin finished, smile fading. “Why would Father do that?”

“Because he’s obsessed with his idea,” Mephisto replied. “He is going to do everything in his incredible power to make his plan work, which is why you have to use your own considerable power to stop him.”

“But,” Rin frowned, “why me? I can’t stop Father, he’s way too strong!”

“Because you are both the son of Satan and half human.” Mephisto crouched to look Rin in the eye. “You belong to both Assiah and Gehenna, and I am sure that one day you will be just as strong as Father.”

The absolute conviction his brother had in him made Rin feel stronger already. “Ok,” he decided. “I’ll stop him. I don’t want Assiah or Gehenna to be destroyed.” He bit his bottom lip. “But what do I do?”

“For now, you keep watching and listening,” Mephisto told him. “Father can’t ever know what we’re doing or he’ll try to kill you, so don’t talk about it in Gehenna. I’ll bring you into Assiah sometimes when the sun is up so we can talk, alright?”

“Alright,” Rin agreed seriously. Mephisto patted him on the head and stood. “Now can we have cake?” he asked, smile breaking out again.

“Brother has cake?” Amaimon asked, popping into Mephisto’s office. He levitated while sitting. “Whee!”

“Amaimon!” Rin launched himself at Amaimon, letting the demon catch him and spin him around. He laughed, dizzy, as his brother dropped him to the floor again. “Let’s have cake! Brother wants a corner piece with lots of icing.”

Mephisto chuckled as he cut the cake, already aware of how much Amaimon was enamoured of sweets. It was Rin’s fault for introducing him to sugar in the first place.

* * *

* * *

“Little Prince.”

Rin looked up from his book. Whether he knew it or not, Mephisto only called him that when he was about to say something demon-related.

Mephisto grinned at him from across his desk, sharp canines glinting in the afternoon light. “I will be sending Yukio out on a call in a few minutes.”

“What for?” Rin asked, already knowing that he was going to be following his twin secretly.

“The lovely Madam Moriyama, who runs the supply shop, has a daughter who takes care of their garden,” the demon king said. “A dekalp seems to have taken root in the garden.”

“A plant demon?” Rin scoffed. “They just like mischief. All of Brother’s kin are like that.”

“Ah, but just like Amaimon, they all sometimes take their entertainment a bit too far,” Mephisto pointed out. “This one is spreading roots into Miss Moriyama and feeding on her obsession with the garden.” Rin was still unconvinced, so Mephisto played his trump card. “I do not like how strong it is becoming, Little Prince.”

Rin sighed. Mephisto had always taught him that part of his role was to keep demons from gaining too much strength in Assiah and creating too much havoc. Strong, wild demons ran the chance of infecting too many people with Temptaints and causing a panic. It was better if fewer people could see demons. Besides, Amaimon never could be trusted to keep a good eye on his kin.

“If it’s just the one dekalp, why do I have to watch Yukio exorcise it?” Rin groaned, standing.

“Because I do not trust anything related to Amaimon to go as I expect,” Mephisto said blithely. He tossed a key to Rin. “That will take you to the road leading to the supply shop.”

“Okay.” Rin shrugged his jacket on over his shoulders. “Anything else?” he asked as he ran his fingers over the sheaths tucked into his sides to check his long knives.

“Do not let him see you this time, Rin,” Mephisto warned. “I do not mind that he knows you are watching his classes, but he cannot know he is not trusted as an exorcist. His complaints could cause trouble with the Vatican and the Grigori.”

“Right.”

Rin stuck the key into Mephisto’s office door. As he opened it and stepped into the bright sunlight, he heard the demon calling Yukio’s phone behind him.

“Yukio, dear! I have a little job for you…”

* * *

“Yes?” Mephisto asked without turning away from the window. The stars were hidden by clouds, but the lights of the town sparkled like stars held down to earth.

“He’s unorthodox.”

Mephisto hummed, pressing his fingertips together under his chin. “And the dekalp?”

There was the sound of a body thumping into a chair on the other side of the desk. “He dealt with it. Eventually.” A snort. “It had made a sort of deal with the girl. Things didn’t go well when she tried to back out.”

“It took her hostage?”

“Yeah. He started bluffing and the demon called it. He shot her.”

“What?!” Mephisto whipped around, nearly upsetting his chair.

Rin grinned darkly at him, sharp teeth glinting in the low life, and Mephisto was struck once more by how much the youngest demon prince resembled their father. There was a faint blue glow to his eyes that could only be seen in the dark. It was nothing compared to Satan’s fiery magnificence, but it was eerie nonetheless.

“Plant vitamins in a dummy bullet,” Rin explained with a short laugh. There was something slightly vicious about the sound, something…demonic. Unlike his brother, Rin had fully accepted and grown into his heritage. “It let her go, and he got rid of it.”

“I see,” Mephisto murmured. “He is something of a danger, then.”

“We’ve always known that,” Rin replied flatly. “That’s why I’m watching him.”

“Of course, Little Prince.”


	4. Chapter 4

**Notes for the Chapter:**

> A/N: I want to thank everyone for your interest in this story, and your support. This isn't a really big fandom, unlike others that I've written for, so it's really great to get such wonderful comments from people who love the story. Thank you!

Rin jumped on his bed, trying to jump high enough to catch one of the little demons floating around near the ceiling. They looked weird, like some mad scientist had mushed together a cat and a tadpole.

“What are you up to now, Little Prince?”

“Astaroth!” Rin leapt off the bed and threw himself at his brother. “I’m trying to catch one of those thingies.”

Astaroth hugged him and set him down. “They’re called coal tars,” the demon said. “They belong to me.”

“Oh.” The bright smile slid off the nine-year-old’s face. “Do you mind that I’ve been chasing them? I can stop if you want.”

“Not at all,” Astaroth grinned. “They’re just silly little things anyway.”

“Okay,” Rin smiled again.

A shape dropped from the ceiling beside them, making Rin jump. The new demon had green hair that came to a point at the top of his head between green horns and scaly, muscled green arms. Rin though he looked like a lizard with all that green.

“Your coal tars are all over my garden, Astaroth,” the green demon said.

“Where have you been, Amaimon?” Astaroth demanded. “Father will be angry you weren’t here with everyone to meet Rin.”

Amaimon shrugged. “I was in Assiah. What’s a Rin?”

“Me,” Rin said, a bit offended. He glared as Amaimon studied him with a blank face and wide eyes. His tail twitched in annoyance, and he knew his flames were glowing brighter.

“A half-demon with Father’s flames. Interesting,” the green demon said to himself. “Your tail is out, Brother.”

Rin gaped as Amaimon just walked away. “What was that all about?”

“That was Amaimon,” Astaroth replied. “He’s the youngest of the demon kings, besides you of course.”

“I don’t think he likes me,” Rin said quietly.

Astaroth squeezed his shoulder with one big hand. “He doesn’t know you yet, Little Prince,” he reminded Rin. “Amaimon is…odd. He’s like a child.” The horned demon smiled down at the youngest son of Satan. “I think, once he knows you, Amaimon will like you most of all.”

Rin wasn’t sure, but he nodded anyway.

“Oh!” Astaroth clapped his hands together, grinning widely. “I almost forgot. I have something for you. I’ve been watching you chase my little coal tars since you came here, so…ah ha!” He produced something from his pocket and presented it to Rin with a flourish.

“A net!” Rin cried, taking the gift. “Thanks, Astaroth!”

Astaroth laughed at his excitement. “You are welcome, Little Prince. Now, how about we go catch those pesky coal tars floating around in Amaimon’s garden? That’ll make you great friends, I’m sure!”

* * *

* * *

 

High in the rafters of the gymnasium, Rin watched the would-be exorcists flee in the face of giant frogs. Well, Reapers, but Rin had always preferred to think of them as just big, ugly frogs. Kind of stupid. The humans were too emotional, because the Reapers were four times their size, and the frog demons were picking up on it.

What a disaster.

A handful of coal tars drifted out of the shadows and floated toward him. Rin scooped one out of the air and scratched between its tiny cat-like ears with a fingernail.

“Hello, little ones,” he murmured. “How are you?”

The coal tar in his hands closed its eyes, rolling its tiny body around against his fingers.

“Like that, huh?” Rin smiled. The other dust demons bumped against his fingers, jealous for his attention. “What are you all doing here? This isn’t your kind of place.”

One of the coal tars nudged against his face, then floated away. It looked back at him as if wanting to know why he wasn’t following.

“Oh, I see.” Rin stood on the narrow steel beam and stretched. “Well, lead me to him.”

* * *

 

The coal tars led him to small, unused room in the cram school. The single window was covered, but Rin had expected that. Astaroth liked the dark.

“Little Prince!”

Rin let Astaroth pick him up and swing him around in a circle. “It’s good to see you, Astaroth,” he said, hugging the demon back. “What are you doing here?”

“Can’t I miss my brother?” Astaroth grinned. “It gets boring in Gehenna now that you’re gone. Mephisto’s always here, Lucifer is off doing whatever it is he does, and Amaimon is with you whenever he can be.” The tall demon sighed dramatically. “Satan is so very dull when he’s plotting, you know.”

“Oh, alright,” Rin teased. He cupped his hands and summoned a small fire between them, creating just enough light to see a desk to sit on. “Yeah, I’ve had a hell of a time trying to keep track of Brother.”

“He’s jealous.” Astaroth sat on a desk opposite him, tapping out an uneven beat with his sharp nails. “You left him behind in a place he sees as your home to watch over a human.”

“A human who is my twin,” Rin pointed out.

“A twin who turned his back on you six years ago,” Astaroth countered. He sighed. “Amaimon has always been alone. He is mischievous, and that has always angered Father more than it pleased him. He hardly notices Amaimon. Mephisto cares for him, but he is more of an authority than a friend. I would say Amaimon never really had a friend, until…”

“Until I showed up,” Rin finished slowly. “What about Behemoth?”

Astaroth snorted. “A hobgoblin can hardly relate to a demon prince. As smart as that little menace is, it is you he’s formed a real connection with. I think he feels like you’ve left him behind, that you don’t think he is as important as this human you’re watching.”

“Of course not!” Rin’s fire flared up with his anger. “I would never just leave Amaimon!”

“I know.” Astaroth stood and swiped a hand through the air. The surface of the world turned brown and crumbled, seeming to rot away as the older demon’s Gate opened. “But I’m not the one you need to tell.” The Gate swallowed up Astaroth and closed with a nearly-audible rumble.

Rin sat and stared at the flames in his hands for a long moment. “Do I still need to tell you, or did you hear enough to know?” he called out eventually.

Amaimon dropped from the ceiling to the desk beside him without a sound. “You really wouldn’t leave me?” he asked in a whisper.

“Never,” Rin promised. He curled his tail around Amaimon’s waist and pulled the demon closer. “Never.”


	5. Chapter 5

Rin was vaguely aware that he was moving. It wasn’t him doing it, though. Someone was carrying him, cradling his little body gently against a larger chest. Rin could see a glow through his closed eyelids that he thought was that same strange blue fire that was the last thing he remembered.

Then he remembered that Father Fujimoto was dead and let out a pained noise.

“Hush, Little Prince,” the person carrying him said. The man’s voice was deep. “It’s alright. I’m taking you to someone who can help you.”

Rin blinked his eyes open to see blue flames all over his body. He was on fire! He started to struggle but was only held tighter.

“Stop that,” the deep voice scolded lightly.

Rin looked up at the man carrying him and nearly screamed. It wasn’t a man at all; it was a monster! He was very tall with messy almost white hair, pointed ears and a huge set of curly horns on his head.

“W-What are you?” Rin stuttered out, terrified.

The creature smiled at him, showing off a set of sharp teeth. “A demon, of course,” he replied. “You would think the old man would at least teach you that much,” he added in a mutter.

Rin struggled again, but the demon held him so he could hardly move. “What do you want with me?” he demanded.

The demon frowned, and Rin noticed that – despite the sharp teeth and horns – the expression was more confused and concerned than scary.

“I want to keep my family safe, little brother.”

“Brother?!” Rin gasped. “I’m not a demon! I’m NOT!”

“You’re on fire,” the demon replied dryly. “And you have a tail.” He shifted a hand, tipped with pointed black nails, and held up a tufted tail that also glowed with blue fire.

“T-That’s…mine?”

“Of course.” Something twitched, and Rin saw the demon’s own spade-ended tail waving at him.

“No…”

“The old man raised you, but he was never your father,” the demon said. His face was surprisingly gentle. “You are the son of Satan.”

“I’m…no…” Rin choked. He felt so overwhelmed. His father was dead, but his father had never been his father, and he was a demon, just like everyone said. Helpless and confused, he began to cry.

“What are you doing? No, don’t cry! Please stop…oh, Samael will have my horns.” The demon sounded so flustered. He shifted Rin from lying in his arms to leaning against his shoulder. “Hush please, Little Prince.”

Rin wrapped his arms around the demon’s neck and cried into his shirt. The demon held him tightly, rubbing his back until his tears dried.

“What have you done to him?” a new voice demanded as they came to a stop.

“Nothing!” the demon objected. “I told him he was Satan’s son and he just started crying!”

“Astaroth, you idiot!” the new voice scolded. “The boy is nine years old, a _child_ , and he just watched Fujimoto die. He was not ready to be told about Father yet!”

“Sorry,” the demon – Astaroth – mumbled. He set Rin down to stand on his own, and the boy grabbed his hand tightly. Rin didn’t know why, but he felt kind of safe with Astaroth. Even if he was a demon.

The second voice belonged to the most brightly dressed person Rin had ever seen. Rin thought he looked like a clown, but he had pointed ears and sharp fangs when he smiled.

“Hello, Little Prince,” he said. “My name is Mephisto, and I am your oldest brother.”

* * *

* * *

 

It was shaping up to be a hot, dull day. There was a ghost haunting the amusement park, and Mephisto had ordered him to take the exorcist students to catch it. Ghosts were a bit unpredictable but usually pretty boring. The one in Mepphyland was only playing little tricks, so it was safe enough for the students to go after.

Yukio leaned against the base of the statue of Mephisto with a sigh. At least he hadn’t seen hide nor hair of Rin, or tail for that matter. The young demon had not been far from his thoughts since Rin had first showed up in his classroom, and thinking about Rin always made his blood boil.

Yukio jumped as something small and sharp tapped on the top of his head. He looked around him, seeing nothing until he looked straight up.

Curious green eyes looked down at him from a blank face. “You’re the one Little Brother is always watching,” the green-haired demon said. “You don’t seem very fun.”

“Demon prince,” Yukio spat. He pulled out a gun and fired off three shots, but the demon leapt out of the way.

Amaimon studied Yukio listlessly. He unwrapped a lollipop and stuck it in his mouth. “No fun at all,” he said around the sweet. “I don’t see why Rin gets so worried around you.”

Yukio aimed his gun at the centre of the demon’s head. “What do you want?”

Amaimon sighed. “I’m trying to get to know my youngest brother.”

“What?”

“You’re Rin’s brother,” Amaimon pointed out. “That means you’re my brother, too. I like having one little brother. Two little brothers would be even better.”

“I’m not part of your demon family,” Yukio scowled. He pulled the trigger again and again, but the demon launched into a series of blindingly fast flips and cartwheels, dodging every silver bullet aim his way.

“Damn it!” Yukio growled. He dropped the empty clip and slammed another one in.

“Stop.”

Yukio dropped the gun from suddenly nerveless fingers. He gasped as a thin line of cold steel pressed against his throat. He sighed, knowing any move to get another gun would end his life.

“Rin!” Amaimon cheered. He executed one last flip to hover cross-legged in the air. “Your brother’s no fun.”

“I know,” Rin agreed. He stepped back and sheathed his knife again. “He doesn’t want to play with you, Amaimon.” The King of Earth pouted a bit and vanished in a puff of green smoke.

Rin chuckled. “Show off.” He picked up the young exorcist’s gun and spun it around a finger by the trigger guard. “You’re too much of a prodigy not to know the King of Earth when you see him,” he remarked.

Yukio slumped back against the statue of Mephisto. “Yeah, I know him.”

“Good.” Rin suddenly pressed the barrel of the gun against Yukio’s forehead. “If you ever hurt him, I’ll destroy you,” he promised coldly. “Brother.”

Yukio watched Rin jump straight up and land on the top of the statue’s hat. Two more leaps carried him out of Mepphyland entirely.

“You aren’t my brother,” he said, but even he could hear the tiny waver in it.

* * *

 

Yukio stopped dead when he saw Amaimon sitting on his bed. Amaimon was slowly tearing long rips in his pillow with sharp nails.

“I don’t like you,” the demon king pronounced. He skewered a feather on one fingernail and flicked it at Yukio.

Yukio withdrew a gun from his belt but didn’t raise his arm. He remembered how protective Rin was of Amaimon. He sat in his desk chair and swallowed his disgust as the blank-faced demon blew on the feather to keep it in the air.

“Why?”

“Because you take Little Brother’s attention away,” Amaimon said with a shrug. “And you make him sad. I don’t like it when Rin is sad.”

Yukio was surprised by the small shock of pain that went through him at that statement. “What makes him sad?”

“Because you hate him,” Amaimon replied listlessly. “It hurts him.” He turned dull green eyes on the young exorcist. “I want to kill you for hurting Rin, but Elder Brother says I can’t.”

“Damn right you can’t.” Rin walked through the door. “I’m getting tired of keeping track of you, Brother.”

Amaimon unleashed one of his rare smiles that always melted away Rin’s annoyance with him. “We’re playing that human game. Hide and find.”

“Hide and seek,” Rin corrected.

“Fine. Time to seek me!”

Amaimon leapt for the window, but Rin was faster. He grabbed the King of Earth around his waist and wrestled him to the floor. He wrapped his tail around Amaimon’s eyes and lit it with his blue flames. While the older demon was distracted and blinded, Rin slapped a specially-made collar, fresh from Gehenna, around his neck.

Amaimon stared up at him with enormous eyes. “Brother was not being comedic,” he whispered.

“Nope,” Rin grinned. He added a chain to the collar. “I told you I’d have you on a chain, Brother.”

Yukio shuddered. He wondered if Rin knew how filthy that sounded.

Amaimon jumped up and ran, dragging Rin behind him as the son of Satan held onto the chain desperately. Rin’s laughter echoed through the corridor until it cut out suddenly.

Maybe he didn’t know. But then again, maybe he did. They were demons after all. “Disgusting.”

“Your human ideas bias you.”

Yukio whirled around to see Mephisto sitting on top of his desk, legs crossed primly. He twirled a gun around his finger, and Yukio realised it was the same one Rin had taken from him that afternoon.

“I am human.”

“I know.” Mephisto heaved a dramatic sigh. “Such a pity. Do come back, Little Prince,” he added, raising his voice. “We have things to discuss.” Rin appeared with a soft _pop_ , holding a length of chain in his hands which he draped across the back of his neck.

“I have nothing to say to him,” Yukio sneered.

Mephisto shot him a sharp look. “Yukio, dear, shut up and listen. Someone in this school has been summoning ghouls.” Yukio saw Rin snap to attention out of the corner of his eye. “Strong ones.”

“Is that it?” Yukio asked. There were always demons to deal with. That was why he became an exorcist.

“I haven’t felt any summonings,” Rin said. His eyes had a slight blue glow to them. “It’s someone you’ve given permission to.”

Mephisto bowed his head. Yukio was struck by the idea that he seemed to defer to Rin. The older demon looked almost frightening without his usual smile on his face. “Yes, a specialist of sorts.”

“A specialist in what?” Yukio asked.

Mephisto seemed to choose his words carefully. “One of the few remaining exorcists to know how to create a Naberius.”

Yukio flinched when Rin growled. “And will I feel the summoning of a Naberius, or will your wards prevent that too?” he snarled.

“Brother…”

“Don’t ‘Brother’ me, _Samael_ ,” Rin snapped. “Let me do my job and stay out of my way! I’ll ask for your help if I need it.” He turned on a heel, chain swinging out around him, but Mephisto’s voice stopped him at the door.

“And should I keep Amaimon out of your way as well?”

Rin stiffened, his hand clenching around the doorframe. “Don’t talk about Amaimon, _Teufel_.” Mephisto flinched, and Rin vanished.

Yukio stared at the wood of his doorframe, crushed to match the shape of Rin’s hand perfectly.

**Notes for the Chapter:**

> A/N: ,,Teufel'' is German for Devil or Demon.  
> Can anyone guess why using German would be such a big deal for Mephisto, especially is this context? It's not an easy question, so the first person to get it right will get a little one-shot in this 'verse gifted to them!   
> Thanks so much for reading!


	6. Chapter 6

**Notes for the Chapter:**

> A/N: I know, it's been so long! Real life has gotten in the way of my ability to update. But that's college, unfortunately.
> 
> So, the results of the last chapter's little contest! Tinker_Titan had the first and best answer to my question. Tinker_Titan, if you give me a prompt of something you want to see in this 'verse in the comments, I'll write it up for you as soon as I can!
> 
> Mephisto is based off the demon of German legend called Mephistopheles (part of what drew me to the series, actually). Mephistopheles tempts a human - usually called Faust - to give up his soul in exchange for being Mephistopheles' master for 24 years. Now, for this story, I'm drawing a bit more from the version of Mephistopheles from the English play "Doctor Faustus," one of the first works to be based on the legend after it was first published in the 1580s. In that, Mephistopheles is VERY protective of Faustus, always fearing that he will repent and Mephistopheles will not get his soul after the 24 years. When Rin calls him ,,Teufel," it is meant to remind Mephisto of how protective he was of Faustus then and that the human was a weak spot to Mephisto.

“At nine years of age, I am sure you are capable of following directions.”

Rin felt bad. Mephisto sounded so tired. He didn’t mean to make Elder Brother sound tired.

“I’m sorry,” he said quietly.

Mephisto ruffled his hair. “I know you are. I know you are probably bored with this, too, but we cannot stop now.”

Rin sighed. “Ok,” he grumbled. He folded his legs under himself, closed his eyes and took a deep breath. “Now what?”

“Now you be quiet and listen.”

“I am listening,” Rin grouched. He opened one eye to glare at Mephisto.

Mephisto glared back. “Not to me, _Knabe_ , to yourself.”

Rin huffed and closed his eyes again. “What am I supposed to be telling myself?”

“Listen to your demon,” Mephisto explained. “It will be strong enough to hear now that you are in Gehenna. Let it speak and listen to what it tells you.”

Rin breathed slow and deep, just like Mephisto had taught him, to calm his mind. He tried to think about nothing.

As he made his thoughts quiet, he started to hear a voice. It sounded kind of like his own and he almost ignored it, but it was not saying anything it was thinking. The voice was saying things about pain and blood and chaos and darkness. It was scary, but Rin also felt kind of excited, like his heart was racing and he wanted to laugh.

“I can hear it!” He opened his eyes. Mephisto was smiling at him.

“Good.” Mephisto’s teeth looked sharper than they had before. “Very good, Little Brother.”

* * *

* * *

Days later, the time came. Rin felt the summoning as a shiver down his spine. He whipped his head toward the Academy. Someone had summoned a ghoul far too powerful to control for long. He needed to watch them.

The rubber ball he had been distracted from catching hit him on the side of the face, making him grunt. Behemoth whined when he made no move to retrieve it.

“Sorry, buddy,” Rin apologised. He tossed the ball back to the hobgoblin. “I’ve got go. Go find Brother, ok?” Behemoth pouted at him, looking just like Amaimon, but disappeared with a pop. Rin drew a long knife from his belt and vanished himself.

He reappeared on the roof of the old boys’ dorm that Yukio lived in. Yukio lay against one wall, looking heavily beaten and barely able to hold his gun up for his shaking. He fired shot after shot at the Naberius that was bearing down on him.

One of the older tamers that Rin remembered was called Neuhaus had summoned the thing. It was hardly much of a surprise. Rin had known who was summoning them as soon as Mephisto brought it up. Neuhaus was one of a handful of those who knew how to call forth a Naberius, the only one at the True Cross Academy.

Neuhaus was clearly lost to his hatred, shouting at Yukio. “I will destroy anything connected to Satan! Kill the son of Satan!” he ordered the creature.

Yukio’s gun clicked as he shot his last silver bullet. Rin knew he would not be able to move fast enough to reload before Neuhaus’ familiar reached him. He cursed himself for what he was about to do.

“Yukio Okumura is not the son of Satan,” he said, loud and clear enough for Neuhaus to hear as he stepped out in front of Yukio. He raised his knife and let his flames out to lick along the edge of the blade. “I am.”

He heard Yukio rasp out his name behind him, but his eyes were on the Naberius and its master. The creature let out a roar and turned on him. “I hate ghouls,” he said casually. “They’re too stupid to know their master.” Quicker than human eyes could follow, Rin charged forward and cut through the demon, bursting out in front of Neuhaus as it melted away into black shadows. “Is that all you’ve got?”

Neuhaus’ eyes glinted crazily. He let out a wordless yell and launched himself at Rin, brandishing his oversized compass. Rin eyed the weapon as he braced to deflect it. It was longer and heavier than his knives and more oddly shaped than any traditional weapon he had trained with.

This fight could get fun.

Rin twisted his wrist, sending the compass skittering off the flat of his knife. He spun around to place himself behind Neuhaus. The exorcist turned to meet him, blocking Rin’s thrust with the hinged end of his compass.

“You cannot defeat me, demon,” Neuhaus growled. “I am a fully-trained exorcist!”

Rin sighed. How clichéd. He drew his other knife in answer and swiped at the man’s face. Neuhaus’ peripheral vision was impaired by his missing eye and he jerked back too late. The tip of Rin’s knife carved a shallow groove across his cheek.

Fire welled up in Rin’s chest as the smell of blood reached him. His demonic nature was always stronger in the darkness, and it was a dark, moonless night. Some deep, basic instinct urged him to lick the blood from his knife, to place his mouth over the wound and suck the fresh blood from the source. Rin shook himself, trying to shake off the insistent urging in his mind.

Neuhaus took advantage of his short distraction. He spun his compass around faster than Rin would have thought the aging human capable of and stabbed the point into Rin’s left arm. He dragged it sideways as he pulled it back, tearing through muscle.

Rin howled through gritted teeth and scrambled backwards. He cradled his arm to his side. The sudden pain had cleared his mind of the bloodlust, but too late. Only having one arm would limit him to using only one knife, and one knife could not last for long against Neuhaus’ enormous compass.

Neuhaus’ eyes glittered with insanity, Rin’s blood dripping from the point of his compass. “Not so sure now, are you, demon?”

Rin gripped his knives tighter. Blood welled up in his wound and ran down his arm. He shifted his stance as he approached the exorcist again, sheltering his left arm as much as he could. Neuhaus hefted his compass again and met him in the middle of the roof.

Rin raised his knife high with his good arm, angling it to separate Neuhaus’ head from his shoulders. The exorcist swung first, bringing the deadly point of his compass around and skewering Rin through his right side. Rin screamed as he felt it push through his ribcage and into his lungs. He yanked himself away and tumbled to the rooftop.

“No!” Yukio shouted behind him.

Neuhaus advanced on him, weapon raised high. “Time to die, son of Satan.”

Rin gripped his knife tightly, summoning up his flames once again. He stabbed the knife deep into the surface of the roof. “Gehenna Gate,” he rasped. His Gate opened behind the exorcist, a simple hole of darkness edged in swirling shadows. “Go to hell, human.”

Neuhaus let out a shout as Rin hit him in the chest with a final blast of flames and knocked him backward into the Gate. It closed, swallowing him up.

Yukio had finally recovered himself. He hobbled over to Rin, clutching at his side. “Are you ok, Rin?”

Rin let his flames die out. He drew in a breath that was pure agony. “I need Elder Brother,” he managed before the pain over took him.

**Notes for the Chapter:**

> A/N: ,,Knabe" is German for "boy." Mephisto strikes me as someone who would slip into German when frustrated.


	7. Chapter 7

**Notes for the Chapter:**

> A/N: To everyone who commented on the story so far, thanks for not letting me forget about this story. We all deserve to see it through to the end. This is for you guys.

Rin walked down the hallways that were slowly becoming familiar to him. The citadel of Gehenna, Satan’s home, looked like a castle that had grown out of the rock. Rin didn’t think there was a flat surface or right angle in the whole building, and the corridors reminded the ten-year-old of tunnels. The blue flames that lit everything cast strange shadows.

Rin pushed the door open, careful to keep quiet. Amaimon’s room was dark, so Rin focused very hard to make just a tiny light with his flames in his hand. He picked his way around rocks and holes on the ground until he reached the crater Amaimon had turned into a sort of nest.

Only the top of the King of Earth’s head and the tips of his horns were visible in the pile of covers. Rin debated for a second, then shrugged and jumped onto the pile anyway. He wriggled until he bumped up against his brother. A heavy arm shot out to trap him and Amaimon’s face emerged to blink at him.

“Rin woke me,” he stated slowly.

Rin curled up against his brother’s chest. “I couldn’t sleep.”

“Why?”

“Don’t know.” Rin pulled his tail into his hands and fiddled with the end. “I want to go to Assiah.”

“You want to leave Gehenna?” Amaimon’s wide eyes looked confused and a bit sad.

“No!” Rin sat up. “I live here now, with you and Elder Brother and Astaroth, right?”

“Right.” Amaimon smiled, and Rin thought it was maybe the third time he had seen the older demon do so. “So what do you want to go to Assiah for?”

“I don’t know,” Rin admitted. He fiddled with his tail some more while he thought. “I want ice cream,” he decided.

Amaimon plucked his tail from his hands with two long fingernails. “What is ice cream?” he asked, curious.

Rin grinned. “It’s the best! Cold and creamy and sweet, it’s delicious!”

“Sweet?” Amaimon murmured.

“Yeah! We should go get some! Can you make us a Gate?”

Amaimon tilted his head to one side and looked at Rin. “Ok.”

“Yaaay!” Rin hugged his brother tightly and scrambled out of the pit Amaimon called a bed. “Let’s go!”

* * *

* * *

 

Yukio let out a grunt as the doctor wrapped his ribs tightly. He had three fractures and was lucky not to have broken any outright during his fight with Neuhaus. The fractures were already dangerously close to his lungs.

“Oh my god, sir, are you alright?!”

He sighed as his new class of Exwires poured into the tiny room, led by Shiemi Moriyama. “I’m fine, class.”

“But what happened?” Suguro demanded. “Some of the exorcists are saying Professor Neuhaus was summoning the ghouls and you killed him!”

“He was,” Yukio allowed, “but it wasn’t me that killed him. I…had a bit of help.”

“Who-“

“All set, Exorcist Okumura,” the doctor interrupted. “I expect you’ll want to visit your friend down the hall now.”

“He’s not my-“

“Of course!” Shiemi exclaimed. “Yuki, we’ll go with you to visit your friend!”

“We aren’t-“ Yukio tried again, but the girl was already pulling him off the bed and out the door. The rest of the class fell in behind them, forcing him down the hall.

“Hey, I remember him.” Suguro stopped at the window to Rin’s room. “He’s that demon that talked to you on the first day of class. What’s he doing here?”

“Is he your friend?” Shiemi asked innocently.

Yukio scowled. “No, he isn’t.” He sighed. “He did defeat Neuhaus, though.”

“Why?”

“It’s…complicated. And I’m not sure I know myself.”

Yukio watched Rin toss and turn in the white hospital bed, wincing with every movement. Something in his chest twisted when he realised how young he looked. Rin was only fifteen. They both were, and they were practically waging war. What in God’s name were they doing? How did Rin become someone so strong, someone he hardly knew anymore?

He shoved those thoughts aside. Rin was a demon, that was how. He belonged in Gehenna, not messing up Yukio’s life.

“Poor boy,” Shiemi crooned next to him. She laid one small hand on the glass separating them from Rin’s room. “Shouldn’t he be asleep? He’s hurt, he needs to sleep!”

“Yes, he does,” another voice added. Everyone turned to see Mephisto and Amaimon walking down the hall to them. Amaimon immediately opened the door and went over to Rin. He nudged Rin until the young demon looked up at him, exhausted, and scooted over to make room. Almost as soon as Amaimon was in the bed Rin curled into his narrow body and fell asleep.

“What the hell is that about?” Suguro demanded.

“Rin doesn’t deal well with bedrest.” The answer was out of Yukio’s mouth before he could stop himself. “He’s too active.” He turned to look at Mephisto, steadfastly ignoring the shocked looks on his students’ faces.

Mephisto nodded. “He used to come knocking at my door in the middle of the night.”

“Sometimes he’s too distracted by his own thoughts. He can always fall asleep with another person, though.” That was yet another memory of his twin Yukio had not given his mouth permission to say. He sighed. “He used to wake me up in the middle of the night when we were little so he could climb into bed with me.”

“WHAT?!” Six voices behind him shouted. Yukio could almost hear the jaws hitting the floor.

Mephisto just looked at him, face blank and head tilted to the side. “You have an excellent memory, Mr Okumura,” was all he said before he left. Yukio knew it was a jab of some sort.

He turned and faced his students. He would have to tell them at least part of the story before they went crazy.

“Rin and I were born twins,” he said quietly. “He’s my older brother. No,” he held up a hand to silence them. “Let me talk. Rin used to get in a lot of fights, especially protecting me. We were nine when our father died trying to save Rin from getting killed by two gang members twice his age because he’d jumped into another fight to protect somebody.” Hot shame burned the back of Yukio’s throat as he remembered the awful way he had treated Rin at the funeral. “I was so sure it was his fault and stopped talking to him. I hated him…”

His words trailed off as he watched Rin sleeping peacefully beside a demon king on the other side of the glass. Suguro cleared his throat. “What about now?”

“Now I know better,” Yukio sighed, “but I don’t think he’ll ever forgive me. The Director took him in and raised him, though I think we can all see who he’s closest with.” Everyone looked at Amaimon, who was combing the tangles out of Rin’s hair with his long fingernails and an intent expression. “Rin’s the most powerful person I could ever meet, but I don’t know anything about him anymore.”

Shiemi put a hand on his elbow. “I’m sure he’ll forgive you someday, Yuki.”

Yukio half-smiled at him. “Thank you, Shiemi. I hope you’re right.”

* * *

Rin felt very out of touch with the world around him. His left side ached whenever he moved and every breath his took burned against his healing lungs. His room was kept dim so he could sleep whenever he needed to, but it was still fairly bright in the afternoon. Rin let out a sleepy mumble and buried his face deeper into the body next to him. The slight scrape of long nails against his scalp told him it was Amaimon, but he already knew from the sense of comfort he felt and the faint smell of dirt and blood.

Amaimon seemed the wrong size, until Rin realised he was used to his brother’s demon form. Whenever they shared a bed in Gehenna, he curled up in Amaimon’s heavy, muscled arms.

“Rin is cold,” the King of Earth muttered.

“Human bodies feel different, don’t they?” Rin mumbled back. “No flames or demon arms.”

“I like it when Rin is warm.” Rin felt Amaimon nuzzle his face into his hair. “I wish you could sleep in Gehenna. You should not have injured your human body.”

Rin grumbled wordlessly. “Elder Brother said human bodies have to heal in Assiah.” He sighed. “I wish I was in Gehenna right now, too. I miss staying in your room in the citadel.”

Rin’s sensitive hearing picked up the noise of someone grinding his teeth. Amaimon shifted beneath him. “The exorcist doesn’t like you talking about Gehenna.”

“Which exorcist? There are exorcists crawling all over this damn place.”

“Hey!”

“The one you watch,” Amaimon informed him blandly.

“Oh.” Rin turned over and blinked at the person sitting in the chair beside the bed. “Yukio.”

Yukio looked…confused. “You talk about Gehenna like it’s your home or something.”

“It is,” Rin frowned. “Oh, you don’t like thinking that someone you grew up with prefers Satan’s realm sometimes? Isn’t that a little rich, since you’re the one that was telling me to go back to Gehenna?” Amaimon tightened his arm around Rin’s waist and pressed his nose to the back of Rin’s neck, making the young demon relax again.

Yukio glared at Amaimon’s arm. “Are you jealous?” Rin asked quietly. Yukio sputtered, eyes wide, but Rin pressed on. “You and I used to be close, until you cut me out of your life for something that wasn’t even my fault. I lost my home because of you, Yukio! I lost the last of my family! What gives you the right to be jealous that I had to rebuild my life?” Rin shouted before he started coughing. He rolled back into Amaimon’s hold when they finally subsided, every breath feeling like knives across his lungs.

“Shirou raised me to be a good human,” he rasped, “but I’m not a human. Satan taught me to be a demon king and the crown prince of Gehenna, but I’m not just a demon either. Mephisto is the only one who accepts me for both parts of what I am.” He heard only silence from Yukio. “And Amaimon. I love Brother.”

“What is love?” Amaimon asked curiously.

Rin scrunched up his nose as he thought. “Love is…when some people are more important to you than anyone else. Then you love those people.” That seemed to be the simplest explanation. Love was a very complicated thing, and Rin wasn’t even sure about it. He only really knew what he had learned before the age of nine. Satan was not much of a loving father.

“Oh,” Amaimon murmured. “I love Rin too.”

Rin could practically feel the anger and jealousy rolling off Yukio behind him as he squirmed – as best he could while in pain – deeper under the covers. “Go away, Yukio,” he ordered. “I want to sleep.”

 

 


	8. Chapter 8

**Notes for the Chapter:**

> A/N: You guys, the support for this story is incredible. You all, everyone who reads and leaves kudos and comments, all of you, are the best. I can only repay you with this short new chapter and hope my sudden (minor) plot twist doesn't drive you all away!   
> What can I say, it's where the story wanted to go. I'm just a passenger here.

Rin cowered into his brother’s side down in the stony pit that was Amaimon’s bed. His small hands gripped tighter with every noise that filtered through the door. His usual blue flames were low from his fright, making the room dark.

As soon as news of the rebellion had reached the Citadel, Mephisto and Astaroth had pushed him into Amaimon’s room and left to fight. Amaimon had done something with the stone walls that covered the place where the door had been.

“It will be over soon,” Amaimon promised. “If Father goes to fight, it will be over soon.”

Rin wanted to cry. In nine years of living with old Fujimoto and six months in Gehenna, he had never heard such terrible noises. There were screams and clangings and horrible, crazy laughter that made Rin’s stomach flip over. The noises sounded like they were getting closer, too.

“Stay here,” Amaimon said suddenly. He left Rin alone as he rummaged through a pile of stuff in the back corner of the room. Rin wrapped his arms around himself, shaking.

He jumped when a large, scaly hand touched his shoulder. Amaimon put a long knife in his hand. “Use it if you have to,” he said in a flat voice without any of his usual innocence.

A burst of shouting at the door made them both turn. Someone started pounding on the stone wall. Amaimon crouched and wrapped his thick tail around Rin protectively.

The stone cracked and splintered. Rin pressed his face into Amaimon’s shoulder to shield his eyes.

“It’s done!”

Rin recognised Astaroth’s voice and looked up. The King of Rot was covered in blue-black demon blood from his horns to the swords in his hands. He grinned, and Rin saw more blood on his sharp teeth.

“It’s over, Rin. It’s safe now.”

Rin buried his head in Amaimon’s chest and cried.

* * *

 

* * *

Deep under the Japanese exorcist headquarters, training room 7 was tightly locked.

Rin braced his hands on his knees as he tried to control his breathing. His lungs had not yet fully healed from his fight with Neuhaus. The doctor left his place in the corner, stepping over trails of blue fire as he moved to treat Rin’s fallen opponents. He had tried not to maim them – it was only a training exercise, after all – but some of their gashes might need stitches. He had a cut of his own, a shallow one near his left elbow, that was already closing up.

A slow clapping reminded Rin of the man who had arrived midway through the fight.

“As vicious as always, demon.”

Rin smiled darkly. “High praise coming from you, Angel.”

Arthur Auguste Angel chuckled as he stepped gingerly over the still-smouldering swathes of Rin’s flames. “I heard you were injured while fighting a _Naberius_ , of all things. I wondered if you’d lost your edge.”

“Nope.” Rin licked the human blood off his knives, relishing the way Angel shuddered. “As vicious as always, like you said.”

“Well,” Angel cleared his throat. “I suppose that is good.” He frowned when Rin laughed at him. “There is a pair of demon kings looking for you.”

“Lead the way, and I’ll make three of a kind.”

Rin bowed lightly to his training partners and followed Angel out. Mephisto and a sullen, bored-looking Amaimon met them on the way to the surface.

“The Vatican is beginning to investigate Neuhaus’ death,” Mephisto said bluntly, unusually business-like. “They will be calling you to give testimony soon.”

“Let them.” Rin shrugged. “The Grigori know I am willing to work fairly with them under daylight. I’m sure they know more about the Summoner’s activities than I do.”

“Unfortunately, very little is known at the moment.” Mephisto sighed. “They believe there is a chance you have imprisoned Neuhaus somewhere in Gehenna.”

Rin snorted and laced his fingers with Amaimon’s. “They really have no idea what Gehenna is like, do they?” he asked rhetorically, looking at his favourite brother. Amaimon shook his head. “I sent the exorcist to Astaroth. You know as well as I do how Astaroth treats prisoners.”

Mephisto frowned. “Indeed I do. I shall pass it on to the Grigori.”

“Let’s go to Rome, Rin,” Amaimon said suddenly. “We should go see the pagan temples.”

“Alright,” Rin agreed fondly. He turned to the man who had been forgotten during their conversation. “It was good to see you again, Angel. I’ll try to visit after I give testimony.”

“Of course, demon,” Angel nodded. “I’ll find some good tea.”

Rin laughed. “You’d better! You know I don’t drink that cheap crap.”

“ _Ri-iiin_ ,” Amaimon whined, pulling on the half-demon’s hand. “Let’s go!”

“Alright, alright, I’m going!” He let Amaimon guide him through his Gate in the stone wall. The Gate closed behind them, cutting off Rin’s echoing laughter.

“That is the first time you have seen them together, is it not?” Mephisto asked quietly.

“It is,” Angel agreed.

“I have been silent about your … fondness for Rin before.” He pinned Angel with a piercing gaze. “He was young when you became Paladin, though more mature than any human, and you are an honourable man.”

Angel swallowed hard. “Why break your silence now?”

Mephisto sighed. “My young brother understands far more than he shows, and he is a trickster besides. He is aware of what he is doing, and he knows he has a demon’s eternity to ease Rin into a romantic relationship.”

“Are you asking me to step back?” Angel sneered.

Mephisto shook his head. “Merely informing you of your opponent. If you desire him, you cannot continue as you have been, waiting for Rin to become aware of your affections on his own. He will not, it is not in his nature. You must be blunt.”

He gave the stunned Paladin a cunning smile and vanished, leaving Arthur Auguste Angel spluttering.

 

 


End file.
